[jeff5may]

Originally Posted by buffalobillpatrick

One of these on pipe at pump output:

30PSI Pressure Transducer or Sender for Oil Fuel Diesel Gas Water Air | eBay


Take pressure reading with pump off, turn on pump, take a 2nd pressure reading, calculate Delta, calibrate with good known flow.

That's a fuel pressure sensor! For what kind of vehicle might I ask? I bet you could find one of those bad boys at autozone for 8.99 if you knew what kind of car it went in. Ingenious.

I must have been working nonstop that month, I'm still playing catch-up today.

EDIT: OK, I'm caught up now. And here come the questions:

So for the water-source variant, the analog fuel pressure type sensor will be used for proving coolant flow downstream of the heat exchanger, yes? To me, this means an interrupt will not be needed to count flow pulses, which will greatly simplify debugging. A simple periodic sampling can be done instead, which can be used during the start-up routine to determine a baseline setting while the compressor is locked out.

Another detail comes to mind: do you still want temperature sensors in the same places as these pressure sensors also? And in other places also? Sounds like a lot of analog pins.